The present invention relates to a switching element, in particular a pressure-wave switch for safeguarding jamming points in the case of operable gates, doors or the like, having at least one pressure chamber which is provided at least partially with a diaphragm, it being possible to connect an exciter contact element for making contact with a consumer contact element via the diaphragm.
Such pressure-wave switches are known and can be obtained on the market in a wide variety of forms and designs. They serve essentially to safeguard jamming points, in particular in the case of operable doors, gates or the like. Use is frequently made of sealed rubber or hollow sections which are connected via a hose to a pressure-wave switch described at the beginning. Given a specific pressure on the hose when, for example, a door, a gate, window or the like is closed, a pressure is built up in the pressure-wave switch and an electric contact is closed between an exciter contact element and a consumer contact element. If the door is opened, the pressure in the pressure-wave switch subsides, the diaphragm retracts and an electric contact is interrupted. The latter conducts the corresponding signal, which can be further processed.
In this case, a contact element which is assigned to the diaphragm is moved linearly against a further contact element of a consumer contact element. Contamination and, in particular, wear phenomena frequently occur as a result with such pressure-wave switches. Through frequent operation, electric arcing forms a so-called insulating layer which greatly impairs the reliability of such a pressure-wave switch. Such switches are frequently moved, and so very high demands are placed on wear. These switches react, for example, in the case of an air overpressure in the system of approximately 2 mbar. Upon contact closure, a stop signal or a reverse signal can be passed on at the drive of the door or the gate.
The reliability of such pressure-wave switches is therefore of fundamental importance in safety engineering. Operations frequently proceed in this case with contact gaps and low contact pressures, resulting in contamination, oxidation of the contacts even in the case of low currents such as occur, for example, in driving digital circuits.